In general workbenches prior to this present invention usually adopt work tables composed of thick wooden plates or metal plates, which are formed with a plurality of throughgoing bores into which pegs of clamping devices may fit. However, in this way, the clamping devices fixed to the workbench will not be permitted to move or change its orientation in position as users may wish. The prior art devices can be used strictly only for clamping common workpieces, but not for those of peculiar or deviated shape and size, since it is fixed and unable to move.
Further, it has been found that such known workbenches have many pre-determined throughgoing bores made on the work table, used to meet the requirement of possible position change. Yet, this structure is not adequate, not only because it is wasteful of time and labor for assembling and disassembling the clamping devices, but also the pre-determined bores do not necessarily meet the practical need. Thus, it is hard to ensure that the working process and the stability of workpieces clamped will not therefore be affected. So, those known workbenches are still unable to be entitled as ideal workbenches.